Blueprint of Life Flashcards
1
Q
what is the genotype of pure breeding plants?
A
homozygous
2
Q
What did Walter Sutton (1902) find?
A
Studied chromosomes in testis of grasshoppers. He found that:
- chromosomes carry genes,
- random segregation and independent assortment (suggested by Mendel) relate to chromosomes separating and sorting into gametes.
- Chromosomes occur as homologous pairs
- Each chromosome carries many genes
3
Q
What did Theodore Boveri (1900) find?
A
Studied meiosis in sea urchins and found:
- Chromosomes are in the nucleus
- a complete set of chromosomes is needed for normal development of an organism.
- Gametes contain half the normal amount of chromosomes.
- Following fertilisation there are full sets of chromosomes and then organism grows. This also showed the importance of chromosomes and that not all chromosomes are the same.
4
Q
What did Thomas Morgan do?
A
Bred fruit flies, (drosophilia) to study genetics. 1910*
- Crossed white male with red female.
- Crossed red male with red female from F1 generation.
- Crossed white male with heterozygous red female.
The results did not follow normal mendellian genetics/ratios. He suggested the results occurred because the gene was carried on the X chromosome. This helped confirm the link between chromosomes and inheritance.
5
Q
What did Mendel (in 1860’s) do?
A
Worked with pea plants. He studied a large number of characteristics e.g. wrinkled seeds. He used pure breeding lines of seeds (always produce particular traits) which he then used to do his hybrid plant experiments. He did a large number of trials using artificial pollination. He made an exact count of offspring to study the identifiable traits. His work showed that traits not present in one generation could appear in later generations e.g. recessive.
6
Q
what is law of random segregation?
A
allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. Each of the halpoid gametes only gets of the particular allele.
7
Q
What did mendel discover?
A
He discovered that traits can be dominant or recessive and discovered a principle of heredity: the law of random segregation
8
Q
Charles Darwin (1850s)
A
Proposed theory of evolution by natural selection. Wrote “Origin of Species” which had heaps of evidence in it. This enraged the Catholic Church. Theory states organisms most adapted to their environment survive and pass their favourable traits on to their offspring.
9
Q
Alfred Wallace (1850s)
A
Independently proposed evolution by theory of natural selection.
10
Q
What did George Beadle and Edward Tatum (1941) do?
A
- grew bread mould on material that has the minimium materials needed to survive.
- Exposed it to x-rays causing mutations.
- Discarded mould that continued to grow on minimum medium, instead wanting mould that didn’t grow.
- They found that the mould would grow when given one amino acid, showing that one chemical reaction had been stopped.
- This showed one enzyme was damaged by the mutation. Showed that one gene coded for one enzyme (or protein).
- Later changed to one gene-one polypeptide because it was discovered that many proteins are made more than one polypeptide.
11
Q
What was the importance of sutton’s work?
A
Showed how important chromosomes are and explained the reasons for Mendel’s results with the information he found regarding genes being on chromosomes
12
Q
What was the importance of Boveri’s work?
A
Showed importance of chormosomes and not all the same.
13
Q
What were the contributions of James Watson and Francis Crick (1953)
A
Used model building to figure out the structure of DNA. Had slow progress until they used Franklins “photo 51” x-ray crystallography image of double helix DNA structure to produce an accurate model of DNA.
- Used to show that communication and collaboration are vital in science. They may have achieved better results quicker if all worked together.
- The close collaboration between Watson and Crick who had a good relationship, with the aid of Wilkins, enabled them to determine and publish their DNA model first.
- collaboration and communication are vital because it can take advantage of people’s specific skills, enabling developments to happen more quickly.
14
Q
What were the contributions of Rosalind Franklin and Maurice Wilkins (1953)?
A
Franklin was a successful female scientist who used x-ray crystallography to image DNA. The image (photo 51) was clear and accurate showing that DNA was a double helix.
Wilkins was x-ray crystallographer also trying to discover structure of DNA. The two did not work well together. Wilkins gave Franklin’s work to Watson and Crick. The two made almost no progress on structure of DNA when working together.
15
Q
Outline the experiments conducted by Beadle and Tatum
A
Beadle and Tatum exposed bread mould to xrays causing mutations. They discovered that the mutations required additional supplements to survive, unlike their normal counterparts, highlighting how a single genetic mutation can incapacitate specific enzymes (which would have normally provided these supplements). Their experiments led to the understanding that one gene produces one enzyme.
16
Q
Why was the one gene, one enzyme theory changed to one gene, one polypeptide?
A
Found to be false in certain proteins, eg. haemoglobin which has 4 polypeptides chains, whith each chain type controlled by a different gene, New statement more accurate.
17
Q
What were Franklin’s experiences and what did they highlght?
A
- She worked well by herself and clashed with Wilkins, who gave her image to Watson who then gave it to Crick against her wishes.
- She was not allowed to college discussions and was treated as inferior due to her gender.
- Franklins kept her results secret, which may have caused her to not publish them in time for her discovery to be acknowledged.
- Franklins never received due credit for her work, (died of ovarian cancer before nobel prize was awarded) and highlights the poor treatment that female scientists received during that period.
18
Q
What are the chemical components of a CHROMOSOME?
A
DNA and protein
19
Q
The Gamete plays an important role in sexual reproduction because it carries
A
HALF of the genetic info of the parent
20
Q
Outline the work done by Morgan that has led to our understanding of sex linkage
A
Morgan bred fruit flies (drosophila) and observed that the eye colour was not inherited in normal Mendelian ratios. He identified that the white eye colour was common in males and rare in females. He went on to suggest that this occurred because the gene is carried on a sex chromosome that the females get two copies of and the males get one copy of.
21
Q
What are the main steps of DNA replication?
A
- The double stranded DNA is unzipped by an enzyme breaking the hydrogen bonds of the bases.
- The resulting exposed bases pair up with complementary free nucleotides in the nucleus .
- Resulting process leaves two strands of identical copies of the original DNA strand.
22
Q
Why is variation in a species needed?
A
Variation enables a species to change over time which is particularly advantageous to a species in a changing environment.
23
Q
Distinguish btw gene and allele
A
A gene is a section of DNA that contains the instructions to make a polypeptide. The gene has a specific location on a chromosome. Genes control a characterisitic eg. Eye colour, blood type etc. An allele is the alternative form or variation of this characteristic or gene, eg. Brown/blue or A/O
24
Q
Describe the contributions of Boveri, Sutton and Morgan
A
Boveri showed that chromosomes are separate, continuous entities within the nucleus of a cell and that cells with the correct number of chromosomes were able to develop normally
Sutton proposed the chromosomal theory of inheritance, and suggested that Mendel’s inheritance factors are located on chromosomes. He demonstrated the principles of segregation and random assortment using grasshoppers
Using drosophila, Morgan demonstrated that some genes are carried on the X chromosome and others on the Y chromosome leading to an awareness that some genes are sex-linked.
25
What Is the definition of genetic engineering?
Any technique used to alter/change genetic makeup of cells or organisms by inserting, removing or modifying individual genes
Traditionally done by interbreeding *
26
What are methods of genetic engineering? And what happens?
1. Selective breeding: breeding of individuals with desired characteristics only--> sometimes result in new variety of animals
2. Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male --> can decrease genetic diversity however, as desirable characteristic chosen
3. Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep:
1. DNA was removed from an unfertilised egg
2.udder cell from sheep
3. Fuse cells + culture
4. Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
27
What are methods of genetic engineering? And what happens?
1. Selective breeding: breeding of individuals with desired characteristics only--> sometimes result in new variety of animals
2. Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male --> can decrease genetic diversity however, as desirable characteristic chosen
3. Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep:
1. DNA was removed from an unfertilised egg
2.udder cell from sheep
3. Fuse cells + culture
4. Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
28
What are methods of genetic engineering? And what happens?
1. Selective breeding: breeding of individuals with desired characteristics only--> sometimes result in new variety of animals
2. Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male --> can decrease genetic diversity however, as desirable characteristic chosen
3. Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep:
1. DNA was removed from an unfertilised egg
2.udder cell from sheep
3. Fuse cells + culture
4. Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
29
What are methods of genetic engineering? And what happens?
1. Selective breeding: breeding of individuals with desired characteristics only--> sometimes result in new variety of animals
2. Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male --> can decrease genetic diversity however, as desirable characteristic chosen
3. Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep:
1. DNA was removed from an unfertilised egg
2.udder cell from sheep
3. Fuse cells + culture
4. Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
30
What is a locus?
The actual place on the chromosome where an allele is found
31
What are methods of genetic engineering? And what happens?
1. Selective breeding: breeding of individuals with desired characteristics only--> sometimes result in new variety of animals
2. Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male --> can decrease genetic diversity however, as desirable characteristic chosen
3. Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep:
1. DNA was removed from an unfertilised egg
2.udder cell from sheep
3. Fuse cells + culture
4. Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
32
Name a fact that about the process of Dna replication that provides support for Darwin's theory of evolution
mutations of DNA may lead to new alleles.
33
Discuss the beneficial social and environmental impact of a transgenic species
(b) Bt corn is an example of a transgenic species created by scientists.
- more profitable crops and more productive, provides a sustainable food source for populations
- It provides a benefit to society as it reduces the need to spray cotton crops with insecticides. This saves people time and money.
- beneficial as pesticides can kill microbial soil life, which can lead to unsustainable farming practices.
- An advantage to the environment is that Bt cotton reduces the use of insecticides, reducing runoff and the impact of health of surrounding flora and fauna
- research indicates that gm corn has no little/no affect on health (no correlation between increase in disease and increased consumption of BT corn.
34
Define environment
Environment is everything around you including living and non living factors, has physical and chemical conditions.
35
Distinguish between physical and chemical conditions
physical conditions (temp, humidity, rainfall, wind speed) and chemical conditions (pH of soil/water, salt concentrations)
36
Eg of how a change in physical conditions can impact evolution of animals, leading to changes in a species.
Peppered moth-originally light colour to camouflage against tree trunks.
industrial revolution trunks became covered in soot, Moth no longer camouflaged +more visible to predators (birds)- decreased in numbers.
The mutated black form of the moth increased in numbers -had better camouflage and could better survive predation.
after industrial revolution, more pale moths became prominent
37
What 5 areas of study support the theory of evolution
```
palaeontology
biogeography
biochemistry
comparative embryology
comparative anatomy
```
38
What method was used to model natural selection (the aim)
1. Cut out 30 (0.5x0.5) pieces black paper & 30 white pieces.
2. Scatter randomly over A3 white paper.
3. Have 1 individual select as many pieces possible in 10sec-use timer
4. Replace so that offspring produced are 1/2 the number of offspring remaining (Eg. if 20 white were taken, only 10 would remain so offspring for white would be 5)
5. Repeat steps 3. & 4., then record results.
39
What was the conclusion for modelling natural selection?
the greater selection of black paper suggests the model was successful in achieving aim of modelling natural selection. In a predatory-prey relationship those of the prey that are more camouflaged more likely to survive than the more visible members.
40
What was a benefit of the model for natural selection?
• Can be done in short period of time while in nature would take years
• Visual so colours representing variations in population - easy to see changes
• All processes in natural selection modelled
- Accessible resources
-simple method so a clear general understanding gained
-Time frame of 10sec places pressure on individual so there bias is less likely, they just select what is immediately visible.
41
What was limited the model for natural selection?
Oversimplified.
• Predation only method of members being removed from population while some may naturally die etc
• Only one type of variation shown (ie colour)
• All mating result in offspring
-there are other selection pressures not just one, (change in chemical conditions, comp for resources),
-black and white strips could interbreed, initially altering rate of natural selection
-the selection pressure is unclear, an important step in Darwin/Wallace's theory.
-Doesn't reflect the longer time period of natural selection, giving a slightly distorted understanding.
42
How does archaeopteryx support the theory of evolution?
it had reptilian features (clawed fingers, teeth, bony tail) and skeleton, but feathers,wings and wish bone for flight like a bird
Shows evidence for evolutionary pathway from dinosaurs to birds.
43
Australian eg of a how a species changed due to a change in the physical enviro
25 million yrs ago Australia wetter, largely rainforest.
---Kangaroos were smaller, omnivorous and had unspecialised teeth, due to variety of food they ate.
Climate become hotter, more arid, rainforests receded, grass the dominant vegetation.
-----(enviro selection pressure caused) Kangaroos became larger, developed large molars to easily grind the low nutritionally dense grass for digestion. Slicing molars receded due to unvaried diet and they became herbivores.
44
How do fossils provide evidence for the theory of evolution?
Arranging in chronical order (using radioactive isotopes)shows:
- increasing complexity
- transitional forms (Archaeopteryx, lobe-finned fish)
45
How do biogeography provide evidence for the theory of evolution?
The uniqueness of some animals and similarities of others across different nations shows that ancestors found in those regions had adapted overtime to better suit conditions and that isolated species in unique environments can evolve uniquely. Eg. Opossum in South America
Eg. Monotremes are restricted to Australia/Papua New Guinea
46
How does comparative anatomy provide evidence for the theory of evolution?
Similar anatomy of many groups of organisms provides evidence, eg btw many vertebrate groups.
Eg. Homologous Pentadactyl limb (bats, humans, crocodiles, horses) across many vertebrates (divergent evolution)
47
How does comparative embryology provide evidence for the theory of evolution?
Many distinct vertebrates have v. similar embryo shape (gill slits, tail) but only some go on to actually develop these features. Indicates we evolved from a common ancestor.
48
How has comparative biochemistry enabled provided evidence for the theory of evolution?
Recent tech developments (DNA hybridisation & analysis of amino acid sequences) has improved capacity to compare the base sequences of DNA btw different species. The results modified evolutionary relationships and gave greater insight into the evolution of present day species.
49
How do ratites provide evidence for evolution?
```
Biogeography
Emu-Australia
Kiwi-NZ
Ostrich-Africa
Rhea-South America
show how species with a common ancestor in Gondwana land changed due to isolation on different landmasses after continental drift occurred, resulting in different environmental selection pressures.
```
50
What does comparative embryology provide a complex example of?
Homology, structures of embryos very similar but structures carry out different functions as they develop into the organ of the body.
51
What is biochemistry?
The study of molecules and how they react
-recent tech developments eg. DNA hypbridisation and analysis of amino acid sequences has increased our ability to compare molecular structure in different organisms
-by comparing base sequences of DNA across of different organisms it was found the more similar the DNA, the more similar the species
52
What is an example for biochemistry for the evidence for theory of evolution by natural selection?
Amino acid sequence of Hb in chimpanzees identical to humans and v similar to gorillas showing we evolved from a common ancestor. (closely related)
53
Outline 1st hand investigation to observe, analyse and compare the structure of a range of vertebrate forelimbs:
1. Draw/examine/label variety of specimens w. Pentadactyl limbs
2. Relate structure to function
3. Look at a couple of structures, compare and consider how similar and different they are
54
How have advances in technology changed scientific thinking about evolutionary relationships?
Advances in analysis of DNA sequencing (DNA hybridisation, amino acid sequencing) has led to reassessment of some evolutionary relationships
-- realise humans share 99% DNA w. Chimpanzees
+closely related to gorillas, monkeys
WE CAME FROM COMMON ANCESTOR
55
As well as advances in DNA tech, how have advances in computer tech changed scientific thinking about evolutionary relationships?
Discovered relationship btw whales & hippopotamus which share DNA, providing insight into whale evolution--> they were once terrestrial.
56
What has molecular biology strengthened?
The fossil record and evidence for evolution
57
In terms of a mutation that produces an allele that is dominant in a population, what would be expected?
It would spread more quickly through a population than a recessive mutation
58
When can evolution occur and what leads to a change in a population?
When a population is isolated
| Natural selection
59
What does a study of biogeography and the worldwide distribution of species show?
Shows the isolation of populations on different continents and identifies species which have evolved independently on different continents
Eg. Emus and koalas in australia, whilst turkeys are unique to North America
60
Why was Mendel's choice of plant (garden pea) criticism to the success of his experiments?
1. He could grow them in large numbers,
2. they produced new generations very quickly
3. Had easily distinguishable traits
4. Could control pollination and thus the fertilisation of each flower
61
How do mendels experiments show successful scientific technique?
He had clearly defined aims, methodically repeated his experiments, controlling the variables. Rep of his experiments provided statistical results and he used mathematical analysis to work out ratios for each feature in F1 and F2
62
How did Mendel achieve accuracy?
Quantitative data
| Making exact counts if features and having careful records
63
How did Mendel achieve reliability?
Repeating each genetic cross multiple times and using large sample sizes in each cross
64
How did Mendel achieve validity?
Having a controlled experiment, studying only one characteristic at a time
Using pure breeding plants by ensuring self pollination taking 2 years to do so
Avoidance of cross/self pollination by removing stamen of flowers then sprinkling pollen from another plant onto the stigma
Using garden peas that had easily distinguishable characteristics
Using mathematical analysis to come to these conclusions
65
impact on evolution of plants and animals in regard to changes in physical conditions in enviro?
- eg.humidity, sea level, temp
- changes in phys conditions alters distribution and abundance of species and can lead to long term adaptations.
eg. peppermoth originally pale (more abundant), but mutant black pepper moth became more abundant during industrial revolution due to soot on trees which altered habitat of pepper moth
66
impact on evolution of plants and animals in regard to changes in chemical conditions in enviro?
salinity, pH , water availability
-those best suited to chemical changes will increase where as others wont
eg. bacteria becoming resistant to various antibiotics
eg. mosquitos becoming resistant to DDT
67
impact on evolution of plants and animals in regard to changes in competition for resources in enviro?
- can result in change in species due to members of same/other species competing for food, water, habitat
eg. giraffes developed longer necks to better access food, compared to individuals in other populations that couldn't
68
archeoptryx showed
the evloutionary pathway from dinosaurs
69
advances in technology changed thinking about evolutionary relationships
advances in analysis of DNA sequences thru DNA hybridisation and amino acid sequencing has enabled scientists to realise that humans share 99% of DNA with chimpanzees and that we are closely related to gorillas, monkeys and baboons.
-this provided evidence for theory of evolution
-biochemistry has thus strengthened fossil record (evolution!!)
-
70
developments in technology chimpanzees and gorillas
recent developments in technology have shown there are more similarites between and humans than gorillas and chimpanzees
-this means classification of chimpanzees should be closer to humans then gorillas, showing we had a more recent common ancestor.
71
advances in technology whales
-as well as advances in DNA technology, advances in computer technology have enabled scientists to discover relationship between whales and hippoptamous which shared DNA. --> improved understanding of whale evolution, confirming that whales were once terrestrial.
72
evolution
change in a population's inherited characteristics over generations. It may result in the appearance of a species or the extinction of a species
73
Jeane baptist le mark
1809
traits acquired in an organisms life can be inherited in subsequent generations, causing variational change over time
(challenged creationism)
74
carlos linnaeus
- binomial system of classification of organisms based on similarities, suggesting they could change through hybridisation
- 1735
75
irasmus darwin
-late 1700s
| suggested evolution by acquired characteristics, only the strongest would survive
76
Charles Darwin
1859
- published on origins of species
- proposed species werent unchanging over time but evolved from ancestral species and this occured through natural selection
77
darwins theory was refined when?
- early 1900s
| - refined to include the possibility of punctuated equilibrium
78
how was evolution influenced by society and politics
before darwins theory predominant view was creationsim as promoted by the church
-thus darwins theory was highly controversial, as it challenged the church's assumptions
(from 1600s onwards other bio, had advanced and these also provided support for these theories
79
views on evolution today?
many religious/traditional views that conflict the notion of darwin, especially the notion of shared ancestry between humans and apes
-school boards in many US states have also insisted that creationsim be taught alongside or in place of evolution
80
disregard evolution in schools?
-can affect the integrity of a scientific education
scientific ed:
-often based on the assessment of collected evidence,
-developing these skills can prevent people from believing untruths
81
what are mutations and how can they occur?
- mutations are a permanent change in dna
| - can occur naturally or through mutagenic agents
82
what are the effects of mutations?
- they impact on the polypeptide chain and protein produced
| - being extremely harmful/cause no change/ or cause a beneficial trait exhibited due to new allele trait created
83
are all mutations bad
- can cause a beneficial trait exhibited due to new allele trait created
- evolution occurred through beneficial mutations occurring at the right time, thus not all mutations are detrimental
84
how do mutations impact upon the individual and subsequent generations
- mutations can cause changes to body
| - these are only inherited if the changes occur in the gamete that forms the zygote.
85
What are the types of mutations of dna
- deletion of section of dna
- inversion (section breaks off &rejoin)
- insertion of bases
- substitution of bases
86
what is a mutagen
physical or chemical factor that increases the rate of mutations
87
examples of mutagens:
-radiation (gamma, alpha, beta, UV, xrays)
88
discuss evidence for the mutagenic nature of raditation
1. increase in birth defects and cancer diagnosis following gamma rays released by atomic bombs in hiroshima and nagasaki
2. genetic mutation within offspring as a result of Chernobyl nuclear disaster
3. early scientists dealing with X rays developed cancer later in life.
89
explain how understanding of the source of variation has provided support for Darwin's theory of evolution by natural selection
- variation exists within a population due to random segregation and crossing over in meiosis, (after fertlisation, zygote has unique DNA) and mutations within both asexual and sexual reproduction
- aswell as random mutations that are passed onto offspring and enviro factors such as diet, climate and lifestyle.
- mutations or changes in genetic material can lead to different alleles and proteins.
- beneficial alleles that are inherited are selected over time by natural selection can lead to the evolution of a species or the formation of a new one if they are isolated.
- darwin wasn't able to explain sources of variation within a population, DNA mutation provides a mechanism to explain the sources of variation.
90
explain how understanding of the source of variation has provided support for Darwin's theory of evolution by natural selection
- variation exists within a population due to random segregation and crossing over in meiosis, (after fertlisation, zygote has unique DNA)
- aswell as random mutations that are passed onto offspring and enviro factors such as diet, climate and lifestyle.
- mutations or changes in genetic material can lead to different alleles and proteins.
- beneficial alleles that are inherited are selected over time by natural selection can lead to the evolution of a species or the formation of a new one if they are isolated.
- darwin wasn't able to explain sources of variation within a population, DNA mutation provides a mechanism to explain the sources of variation.
91
pros of cloning
- organisms can reproduce in a short period of time, without the need for selective breeding and testing
- advantageous to agriculture industry as enables identical populations to be produced that are disease resistant, hardier (well adapted to the enviro), good quality produce & more produce
92
cons of cloning
- No genetic diversity meaning sudden enviro change could wipe out entire populations
- eg. potato famine in ireland due to little genetic variation in potatoes.
93
what is a transgenic species?
transgenic species are organisms which have genetic material from another species inserted into their genome.
94
THe importance of insulin as a transgenic species
Production of Insulin
Humans who lack the hormone insulin suffer from diabetes. Insulin was extracted from animal pancreas. It was often contaminated and produced side effects.
-To solve this issue, genetic engineering has been used to produce large amounts of transgenic, bacterial insulin safely and efficiently.
95
What is the production of insulin?
Gene splicing has been used to produce insulin from genetically engineered bacterium.
1. A ring of DNA known as a plasmid is taken from the bacterium
2. A cutting enzyme is added to splice the DNA at the required places and allowing it to open
3. Then the same cutting enzyme is used to cut the insulin gene (for the human gene from insulin)
4. The cut out gene is then placed into the open ring of the plasmid where it fits exactly and forms new DNA
5. The plasmid is then placed back into the bacterium
6. Bacterium replicates by cell division
7. Then this insulin can be extracted from these bacterium cells
96
salmon -transgenic species what
salmon is inserted with the gene coding for the protein bovine growth hormone
97
benefits of using transgenic salmon
- larger, faster growing fish
- importance of the use of this transgenic species is that many countries prefer a certain amount of fish in diets and fish farming reduces the depletion of natural populations
98
concerns of transgenic salmon
-fish are kept in ponds, however if they escape into the wild they could upset and destroy natural ecosystems
99
benefits of transgenic bacterial insulin?
- less costly, more availablity for people with diabetes
- easier to produce large amounts
- less likely to produce adverse reactions
- suitable for vegetarians and people of certain faiths
100
disadvantages of transgenic bacterial insulin
-concerns raised by ethical groups with regard to disrupting nature's natural genome
101
ethical concerns for all transgenic species?
should transgenic technologies be used just because they are possible?
-it unnaturally alters species, disrupting evolutionary pathways and relationships.
102
Genetic diversity allows for
environmental pressures to select individuals most suited to an environment (ie so if a change in enviro, whole species won't be wiped out)
103
What is the purpose of genetic engineering andd why is it favoured
to produce desirable characteristics within a population , reducing natural variation. Results in better quality and consistency of crops but reduces their capacity to adapt to environemntal change
104
When farming BT corn what must farmer's ensure?
they grow non-BT corn as well to maintian diversity, ensuring insects andn pests don't become resistent
105
What happens when organisms are manipulated genetically to the gene pool of their species?
eg through use of recombinant DNA to make transgenic species, new genes are introduced to species' gene pool inrecasing genetic diversity. This has been used to created disease resistant BT corn and cotton, as well as faster growing salmon.
106
what is dna hybridisation?
where a single strand of DNA from one organism (eg a human) is added to a single strand of DNA from another organism (eg. a chimp) and the number of matches between the abses is measured to see how similar or different two speices are,. If there are a large no. matches then organisms shared a common ancestry recently, while if there are fewer, they they have diverged much earlier and different selective pressures have led to different genes becoming common in their speicies.
